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Wednesday, February 24, 2016

The surface of the Sun radiates light and heat at approximately 5,500 °C. The Earth is much cooler and so radiates heat back away from itself at much longer wavelengths, mostly in the infrared range. The idealized greenhouse model is based on the fact that certain gases in the Earth's atmosphere, including carbon dioxide and water vapour, are transparent to the high-frequency, high-energy solar radiation, but are much more opaque to the lower frequency infrared radiation leaving the surface of the earth. Thus heat is easily let in, but is partially trapped by these gases as it tries to leave. Rather than get hotter and hotter, Kirchhoff's law of thermal radiation says that the gases of the atmosphere also have to re-emit the infrared energy that they absorb, and they do so, also at long infrared wavelengths, both upwards into space as well as downwards back towards the Earth's surface. In the long-term, thermal equilibrium is reached when all the heat energy arriving on the planet is leaving again at the same rate. In this idealized model, the greenhouse gases cause the surface of the planet to be warmer than it would be without them, in order for the required amount of heat energy finally to be radiated out into space from the top of the atmosphere.[1]

The greenhouse effect can be illustrated with an idealized planet. This is a common "textbook model":[2] the planet will have a constant surface temperature Ts and an atmosphere with constant temperature Ta. For diagrammatic clarity, a gap can be depicted between the atmosphere and the surface. Alternatively, Ts could be interpreted as a temperature representative of the surface and the lower atmosphere, and Ta could be interpreted as the temperature of the upper atmosphere. In order to justify that Ta and Ts remain constant over the planet, strong ocean and atmospheric currents can be imagined to provide plentiful lateral mixing. Furthermore, any daily or seasonal cycles in temperature are assumed to be insignificant.

The model will find the values of Ts and Ta that will allow the outgoing radiative power, escaping the top of the atmosphere, to be equal to the absorbed radiative power of sunlight. When applied to a planet like Earth, the outgoing radiation will be longwave and the sunlight will be shortwave. These two streams of radiation will have distinct emission and absorption characteristics. In the idealized model, we assume the atmosphere is completely transparent to sunlight. The planetary albedo αP is the fraction of the incoming solar flux that is reflected back to space (since the atmosphere is assumed totally transparent to solar radiation, it does not matter whether this albedo is imagined to be caused by reflection at the surface of the planet or at the top of the atmosphere or a mixture). The flux density of the incoming solar radiation is specified by the solar constant S0. For application to planet Earth, appropriate values are S0=1366 W m−2 and αP=0.30. Accounting for the fact that the surface area of a sphere is 4 times the area of its intercept (its shadow), the average incoming radiation is S0/4.
For longwave radiation, the surface of the Earth is assumed to have an emissivity of 1 (i.e., the earth is a black body in the infrared, which is realistic). The surface emits a radiative flux density F according to the Stefan-Boltzmann law:

where σ is the Stefan-Boltzmann constant. A key to understanding the greenhouse effect is Kirchhoff's law of thermal radiation. At any given wavelength the absorptivity of the atmosphere will be equal to the emissivity. Radiation from the surface could be in a slightly different portion of the infrared spectrum than the radiation emitted by the atmosphere. The model assumes that the average emissivity (absorptivity) is identical for either of these streams of infrared radiation, as they interact with the atmosphere. Thus, for longwave radiation, one symbol ε denotes both the emissivity and absorptivity of the atmosphere, for any stream of infrared radiation.

Idealized greenhouse model with an isothermal atmosphere. The blue arrows denote shortwave (solar) radiative flux density and the red arrow denotes longwave (terrestrial) radiative flux density. The radiation streams are shown with lateral displacement for clarity; they are collocated in the model. The atmosphere, which interacts only with the longwave radiation, is indicated by the layer within the dashed lines. A specific solution is depicted for ε=0.78 and αp=0.3, representing Planet Earth. The numbers in the parentheses indicate the flux densities as a percent of S0/4.

The equilibrium solution with ε=0.82. The increase by Δε=0.04 corresponds to doubling carbon dioxide and the associated positive feedback on water vapor.

The equilibrium solution with no greenhouse effect: ε=0

The infrared flux density out of the top of the atmosphere:

In the last term, ε represents the fraction of upward longwave radiation from the surface that is absorbed, the absorptivity of the atmosphere. In the first term on the right, ε is the emissivity of the atmosphere, the adjustment of the Stefan-Boltzmann law to account for the fact that the atmosphere is not optically thick. Thus ε plays the role of neatly blending, or averaging, the two streams of radiation in the calculation of the outward flux density.

Zero net radiation leaving the top of the atmosphere requires:

Zero net radiation entering the surface requires:

Energy equilibrium of the atmosphere can be either derived from the two above equilibrium conditions, or independently deduced:

Note the important factor of 2, resulting from the fact that the atmosphere radiates both upward and downward. Thus the ratio of Ta to Ts is independent of ε:

Thus Ta can be expressed in terms of Ts, and a solution is obtained for Ts in terms of the model input parameters:

or

The solution can also be expressed in terms of the effective emission temperature Te, which is the temperature that characterizes the outgoing infrared flux density F, as if the radiator were a perfect radiator obeying F=σTe4. This is easy to conceptualize in the context of the model. Te is also the solution for Ts, for the case of ε=0, or no atmosphere:

With the definition of Te:

For a perfect greenhouse, with no radiation escaping from the surface, or ε=1:

Using the parameters defined above to be appropriate for Earth,

For ε=1:

For ε=0.78,

.

This value of Ts happens to be close to the published 287.2 K of the average global "surface temperature" based on measurements.[3] ε=0.78 implies 22% of the surface radiation escapes directly to space, consistent with the statement of 15% to 30% escaping in the greenhouse effect.

The radiative forcing for doubling carbon dioxide is 3.71 W m−2, in a simple parameterization. This is also the value endorsed by the IPCC. From the equation for ,

Using the values of Ts and Ta for ε=0.78 allows for = -3.71 W m−2 with Δε=.019. Thus a change of ε from 0.78 to 0.80 is consistent with the radiative forcing from a doubling of carbon dioxide. For ε=0.80,

Thus this model predicts a global warming of ΔTs = 1.2 K for a doubling of carbon dioxide. A typical prediction from a GCM is 3 K surface warming, primarily because the GCM allows for positive feedback, notably from increased water vapor. A simple surrogate for including this feedback process is to posit an additional increase of Δε=.02, for a total Δε=.04, to approximate the effect of the increase in water vapor that would be associated with an increase in temperature. This idealized model then predicts a global warming of ΔTs = 2.4 K for a doubling of carbon dioxide, roughly consistent with the IPCC.

(DJ Strumfels' Note: Δε is being increase from 2 to 4 only to rationalize doubling of CO2 causing a 2K rise instead of 1K; nowhere is the doubling of Δε justified by any physical laws or processes.)

Extensions

The simple one-level atmospheric model can be readily extended to a multiple-layer atmosphere. In this case the equations for the temperatures become a series of coupled equations. This simple model always predicts a decreasing temperature away from the surface, and all levels increase in temperature as "greenhouse gases are added". Neither of these effects are fully realistic: in the real atmosphere temperatures increase above the tropopause, and temperatures in that layer are predicted (and observed) to decrease as GHG's are added. This is directly related to the non-greyness of the real atmosphere.

The earth went from the Oligocene through the Miocene and into the Pliocene as it cooled into a series of ice ages. The Miocene boundaries are not marked by a single distinct global event but consist rather of regional boundaries between the warmer Oligocene and the cooler Pliocene.

The apes arose and diversified during the Miocene, becoming widespread in the Old World. By the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path. As in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent. In the Miocene seas, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems. [5] The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread. The Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the Himalayan orogeny had occurred during the Miocene affecting monsoonal patterns in Asia, which were interlinked with glaciations in the northern hemisphere.[6]

Mountain building took place in western North America, Europe, and East Asia. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the North American Great Plains and in Argentina.

The global trend was towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia got drier as it entered a zone of low rainfall in the Late Miocene.

Climate

Climates remained moderately warm, although the slow global cooling that eventually led to the Pleistoceneglaciations continued.

Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivaled that of the Oligocene. The Miocene warming began 21 million years ago and continued until 14 million years ago, when global temperatures took a sharp drop—the Middle Miocene Climate Transition (MMCT). By 8 million years ago, temperatures dropped sharply once again, and the Antarctic ice sheet was already approaching its present-day size and thickness. Greenland may have begun to have large glaciers as early as 7 to 8 million years ago,[citation needed] although the climate for the most part remained warm enough to support forests there well into the Pliocene.

Life

Life during the Miocene Epoch was mostly supported by the two newly formed biomes, kelp forests and grasslands. This allows for more grazers, such as horses, rhinoceroses,and hippos. Ninety five percent of modern plants existed by the end of this epoch.

Flora

The dragon blood tree is considered a remnant of the Mio-Pliocene Laurasian subtropical forests that are now almost extinct in North Africa.[8]

Unequivocally recognizable dabbling ducks, plovers, typical owls, cockatoos and crows appear during the Miocene. By the epoch's end, all or almost all modern bird groups are believed to have been present; the few post-Miocene bird fossils which cannot be placed in the evolutionary tree with full confidence are simply too badly preserved, rather than too equivocal in character. Marine birds reached their highest diversity ever in the course of this epoch.

Approximately 100 species of apes lived during this time, ranging throughout Africa, Asia and Europe and varying widely in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominid clade, but molecular evidence indicates this ape lived between 7 and 8 million years ago.[14] The first hominins (bipedal apes of the human lineage) appeared in Africa at the very end of the Miocene, including Sahelanthropus, Orrorin, and an early form of Ardipithecus (A. kadabba).[15]

Cetaceans attained their greatest diversity during the Miocene,[16] with over 20 recognized genera in comparison to only six living genera.[17] This diversification correlates with emergence of gigantic macro-predators such as megatoothed sharks and raptorial sperm whales.[18] Prominent examples are C. megalodon and L. melvillei.[18] Other notable large sharks were C. chubutensis, Isurus hastalis, and Hemipristis serra.

Crocodilians also showed signs of diversification during Miocene. The largest form among them was a gigantic caimanPurussaurus which inhabited South America.[19] Another gigantic form was a false gharialRhamphosuchus, which inhabited modern age India. A strange form Mourasuchus also thrived alongside Purussaurus. This species developed a specialized filter-feeding mechanism, and it likely preyed upon small fauna despite its gigantic size.

The pinnipeds, which appeared near the end of the Oligocene, became more aquatic. Prominent genus was Allodesmus.[20] A ferocious walrus, Pelagiarctos may have preyed upon other species of pinnipeds including Allodesmus.

Oceans

There is evidence from oxygen isotopes at Deep Sea Drilling Program sites that ice began to build up in Antarctica about 36 Ma during the Eocene. Further marked decreases in temperature during the Middle Miocene at 15 Ma probably reflect increased ice growth in Antarctica. It can therefore be assumed that East Antarctica had some glaciers during the early to mid Miocene (23–15 Ma). Oceans cooled partly due to the formation of the Antarctic Circumpolar Current, and about 15 million years ago the ice cap in the southern hemisphere started to grow to its present form. The Greenland ice cap developed later, in the Middle Pliocene time, about 3 million years ago.

Middle Miocene disruption

The "Middle Miocene disruption" refers to a wave of extinctions of terrestrial and aquatic life forms that occurred following the Miocene Climatic Optimum (18 to 16 Ma), around 14.8 to 14.5 million years ago, during the Langhian stage of the mid-Miocene. A major and permanent cooling step occurred between 14.8 and 14.1 Ma, associated with increased production of cold Antarctic deep waters and a major growth of the East Antarctic ice sheet. A Middle Miocene δ18O increase, that is, a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the Southern Ocean and the South Atlantic.[21]

Sunday, February 21, 2016

The unbearably low standards in "basics of science" at MIT

The Boston Globe recently published an exchange between legendary
physicist Freeman Dyson and eight of his opponents who are employed by
MIT, including a quark expert and a string theorist:

The second, anti-Dyson text was written by the hurricane
opportunist Kerry Emanuel and by Robert Jaffe, a veteran of quark
theory, and it was signed by 6 more MIT employees. In total, 3 of the
people are physicists; the list includes string theorist Wati Taylor.

It is very obvious that to pretend that they have debunked Dyson, they
felt that they have needed to collect a larger number of "authorities".
The logic based on the "ad hominem fallacy" makes the anti-Dyson reply
totally analogous to the 1931 pseudoscientific rant against relativity
that was named A Hundred Authors Against Einstein.
These 2nd class authors wanted to return physics to the 16th or 17th
century and Einstein replied in a simple way: "If relativity were wrong,
one author would have been enough to show it."

Richard Lindzen (who happens to be one man) wrote an insightful and
amusing third-person analysis of the exchange between Dyson and 8 MIT
employees at Anthony Watts' well-known website:

Dyson and Lindzen are climate skeptics which doesn't mean that they uncritically repeat the words of each other.

On the contrary, most climate skeptics typically avoid the group think
and that's true even "inside" the climate skeptic community. Lindzen's
report shows an example of that characteristic independence. When Dyson
and Lindzen disagree with each other, I mostly agree with Dick although I
am not as pure a Lindzen as he is. ;-)

The most obvious point of a disagreement between Dyson and Lindzen is
that Dyson says that the IPCC says that the science (of climate change)
is settled; and it's the IPCC that is the Urquell of the efforts to
reduce CO2 emissions. Lindzen says that the IPCC says that the science
is work in progress (because the IPCC members' salaries are derived from
the assumption that they keep on doing research so it can't be settled
yet); and the IPCC avoids policy recommendations and dramatic
interpretations which are only later added by activists and politicians.
The IPCC only cooperates passively by not objecting.

I think that Lindzen's description is the more accurate one. The actual
IPCC reports are written by people hired as scientists so they simply
can't pretend that the science is over because that would make their
daily job redundant. And yes, I do think that the actual IPCC reports
are mostly filled with regular science, sometimes boring science and
often legitimate science, and the dramatic oversimplified alarmist
interpretations are added as a bonus by "leaders" and especially
"outsiders".

Well, it's more complicated than that. The bulk of the IPCC reports are
"conventional, often boring science" but that bulk isn't too important.
The summaries are way more important and they're way more
policy-oriented, hysterical, and oversimplified. And even the summaries
are considered too long and complicated by too many people, including
most of the alarmist politicians, so these effectively work with even
more concise (and oversimplified, distorted, and dramatic) summaries of
the summaries. And with summaries of summaries of summaries – which are
equivalent to idiotic hysterical slogans that have almost nothing to do
with the science.

Moreover, one shouldn't forget that the IPCC has three working groups –
and only the first one (focusing on the physical mechanisms of the
"problem") fully agrees with Dick's description. The other two IPCC
working groups are increasingly social and political in character. For
these other two working groups, Dyson's description is increasingly
close to the truth.

There's one additional point where I totally agree with Dick. The main
problem with the alarmist interpretation of the climate science isn't
the magnitude of the climate sensitivity (although I find Lindzen's own
below-1-Celsius-degree values to be more likely than those above 2
degrees); the main problem is that many people love to deduce
far-reaching, sensational consequences out of the effect of CO2 even
though the effect is almost certainly very minor even according to the
IPCC reports themselves.

The "refined" statement about the important role of the humans in global warming is formulated by the IPCC Working Group 1 as:

The IPCC report presents strong evidence that more than half of the climate change seen in recent decades is human-driven.

And many people tend to use the agreement or disagreement
with the statement above as a criterion to distinguish alarmists from
skeptics. Well, like Lindzen, I consider myself a full-fledged denier
but I am totally open-minded about the quote above. In my opinion,
people just don't think carefully and rationally about the sentence
above.

Imagine that the sentence speaks about the recent 60 years or so. In
those 60 years, the global mean temperature could have increased by
something like 0.6 °C – that's the end-minus-beginning difference of a
linear function interpolating the noisy temperature graphs via linear
regression. With these values, the IPCC WG1 "iconic" statement says

The IPCC believes that the mankind has contributed at least 0.3 °C of warming of the globe in the recent 60 years.

Is it true? I honestly don't know. My estimate is that the
right figure is probably below 0.3 °C but the degree of my "certainty"
about that claim is very limited, not strongly exceeding 50 percent. In
other words, as far as I can say, the sentence may be either true or
false. But if the sentence is true, does it mean that there is a reason
for panic or reductions of CO2 emissions justified by the fear of
climate change? The sentence just says that since 1955 when most of the
TRF readers weren't born yet, the temperatures have increased by three tenths of a Celsius degree
because of CO2 (only the partial CO2 contribution is counted in the
temperature figure). This is such a small temperature change that you
just can't feel it on your skin even when it occurs abruptly. It's much
harder to "feel it" if you have to wait for 60 years; and if you need to
deduce the value from careful measurements and statistical analyses
(averaging over the places, days+nights, and seasons) of the
temperatures on the whole globe.

Many people, including those who consider themselves skeptics, just
become totally irrational when they're expected to think about these
matters. The point is that this change of the temperature by 0.3 °C –
and IPCC doesn't really claim to be too convinced about any "faster"
warming trend – is indistinguishable from zero for all practical
purposes. It's a temperature change smaller than the effect of one large
volcano eruption; one El Niño episode.

Or take our very mild winter. We Central Europeans had a nice spring day
today; the temperature has reached 11 °C in the afternoon. People
living in the Eastern part of the U.S. can say something similar; the
western portions of the U.S. enjoy a rather old-fashioned winter,
however.

But now, it's natural for many people to think about the mild winter in
the context of the man-made climate change. By the constant repetition,
people's intuitive thinking – including mine – has been contaminated and
we just can't avoid thinking about "global warming" whenever the
weather is mild or hot. The problem with that knee-jerk reaction is that
the iconic IPCC statement is just "somewhat convinced" that in the last
60 years, the CO2 emissions have contributed at least 0.3 °C. It means
that if there had been no CO2 emissions, the today's high temperature in
Pilsen would be – according to the IPCC statement – not 11 °C but at
most 10.7 °C. Look at these two numbers carefully.

The qualitative point is that according to the scientifically
justifiable evidence, the CO2 emissions have had such a small effect on
the temperature that if there had been no emissions since the World War
II at all, it would make virtually no impact on the fact that the 2015
Christmas had no chance to be a white Christmas in Pilsen! Even if the
CO2 sensitivity were 3 times higher than that, we would have over 8 °C
in the afternoon and the snow (if any) would have no chance to survive.

Dick's point, one that I totally agree with, is that even according to the IPCC Working Group 1,
the CO2 effect is so incredibly weak that it just wouldn't make any
detectable difference for the qualitative things that matter – like a
sunny Czech Christmas in 2015. We have had winds mostly from the South
for a week or two and that makes a difference, especially during a very
strong El Niño episode.

But I have spent too much time with the "flavors of skeptics". In
various contexts, I feel closest to Richard Lindzen or Bob Carter or
other great men. Needless to say, most of the actual confrontation and
disagreement isn't in between pairs of skeptics; it's between skeptics
and the alarmists.

Lindzen says that the reply by the 8 MIT physicists is "sophistic". I
think that the shallow reply by Wati Taylor and his 7 comrades could be
written on an MIT place mat
– what you, an MIT freshman, should tell your family and uncle about
the climate change during the Christmas conversations. I am really
baffled that e.g. Wati Taylor isn't ashamed of adding his signature
under similarly incredibly misleading and sometimes downright false
slogans. This is just so pathetic, Wati. And something is extremely sick
about the MIT physics department when you fail to become an instant
anti-science pariah with this kind of junk.

For example, take the simple and absolutely uncontroversial statement at
the end of Dyson's article that "the main effect of CO2 is to make the
planet greener". Taylor and 7 comrades obviously find this statement to
be an inconvenient truth so they try to hide it in a bizarre demagogic
fog such as

The proposal that the “main effect of carbon dioxide is to
make the planet greener” overlooks the constraints imposed by the
availability of other nutrients and the disruption of the biosphere
caused by the direct effects of climate change.

Wati, can't you see how incredibly demagogic, dumb, and
misleading such a comment about "overlooked constraints" is? Dyson has
said just something that every fifth grader should or must know before
she becomes a sixth grader. Plants eat CO2. In the process of
photosynthesis, with the help of the solar energy coming to the leaves,
the oxygen and carbon atoms are separated while CO2 is removed from the
atmosphere, the chemical energy of the atoms increases by the separation
(it's just like when you are recharging a battery; the carbon and
oxygen atoms are ready to be usefully "burned" by animals or power
plants), the carbon atoms are incorporated to the plants' biomass, and
the oxygen is returned to the air.

It's obvious that because CO2 is the main material from which the
"solid" part of the plants is ultimately built (no, the big tree hasn't
removed the same amount of "solid" material from the soil, it took the
"solid" material mostly from the air!), a higher concentration of CO2
makes the life of the plants easier. Some plant species are very
sensitive about the shortage of CO2; other species are less sensitive.
An "average" plant's growth increases by 0.5% whenever you increase the
concentration of CO2 in the air by 1%.

Microscopically, the plants like a higher CO2 concentration because
their pores may be smaller or less numerous and it's still enough to get
the required amount of CO2 from the air (when and because the CO2
levels are higher). And when the pores are smaller or less numerous, the
leaves lose less water vapor – which evaporates through the pores. In
this way, the plants become more water-efficient and less sensitive to
shortage of water and that's the ultimate reason why they flourish in
high-CO2 environments.

Hundreds of experiments have been performed and hundreds of papers have
been written about these most direct effects of CO2. There exist
greenhouses where the higher CO2 is actively exploited. And I think that
there may exist schoolkids who actually know much more than the basic
wisdom I have sketched above. Now, Wati, are you smarter than a fifth
grader? Do you want to avoid the discussion of all the details by denying the very basic point by Dyson
that the increased plant growth is the most direct effect of higher CO2
concentrations? Can you appreciate how incredibly stupid this denial
is? Are there any people left at MIT who are smarter than a fifth grader
and who will point out to you that you may be a string theorist but
when it comes to basics of biology, you are just a complete, 100%
imbecile?

And it's not just your straight denial of photosynthesis as the main
life process that depends on CO2 levels in the air. There are tons of
other, incredibly stupid slogans in your rant – some of them are written
down explicitly and some of them are written down implicitly. In the
sentence in which you denied photosynthesis (and claimed that Dyson has
"overlooked" something – be sure that he hasn't overlooked anything when
his point was just to make the spectacularly obviously correct claim
about photosynthesis), you also wrote about "the disruption of biosphere
caused by the direct effects of the climate change".

What? Have you lost your mind?

There is absolutely nothing "direct" about the hypothetical effects of
CO2 on the plant's life through meteorological phenomena. According to
the IPCC, the elevated CO2 levels only increase the global mean
temperature by more than 0.3 °C in 60 years with a probability just
barely exceeding 50%, according to their estimate. It is spectacularly
clear that a change of the temperature by 0.3 °C in either direction has
a negligible effect on a plant relatively to the change of the amount
of the available "food" by 40%.

Just think about it from a human perspective. Imagine that you solve
similar problems as a plant. You ate something last week. Next week, you
may either have the same amount of food and the temperatures higher or
lower than 0.3 °C; or you may enjoy the same temperature but the amount
of available food (I mean sugars, fats, and proteins) you may eat will
drop by 30 or 40 percent. Which change is more important or more
directly consequential for your well-being, (a) a temperature change by
0.3 °C or (b) the decrease of food supply by 30 or 40 percent? Do you
realize that by your unhinged anti-Dyson rant, you have picked the
answer (a)? Are you serious?

Now, there are other nutrients beyond sugars, fats, and proteins that
humans need. Does it change anything about the fact that the change of
the amount of sugars, fats, and proteins available to you by 30-40
percent is the most consequential change among those we have considered?
If you realize that the answer is a resounding "no, it changes
nothing", why the hell do you mention other nutrients at all? You're
just trying to make people look at some distractions instead of the key
thing and you must know that, mustn't you? Or are you really a complete
idiot?

And be sure about it, the greenhouse effect of CO2 causes a pretty much
uniform warming across the Earth's surface. It's because by the
diffusion, the CO2 concentration gets quickly homogeneous; and the
greenhouse effect controls the absorption of Earth's thermal radiation
which is always comparable at relatively nearby places of the Earth –
because the thermal radiation is proportional to the fourth power of the
absolute temperature.

The greenhouse effect doesn't change much about pressure and temperature
differences, vortices, storms, precipitation etc. If there is any
influence of the mostly uniform change on the more visible weather
phenomena, it's a spectacularly small 2nd or 3rd order effect. Even the
1st order effect, a change of the temperature by "at least 0.3 °C", was
almost certainly negligible. Now try to calculate the non-uniformities
of the greenhouse effect and its impact on pressure differences or the
ability to increase torrential rains or hurricanes that can influence a
plant. Can these effects be stronger than a 40% increase of the main
"food"? Is your brain enough to see that those influences of CO2 through
the weather patterns are absolutely negligible relatively to the change
of the food by 40%? If you're not, I won't really believe that it is
you who wrote the papers about string theory. In that case, you are dumb
as a doorknob and you must have someone else who was writing them and
you are declared as the author because author lists with unhinged
climate alarmists in them look more politically correct.

And the problems with the rant that you signed go on and on and on. The
rant is very short but literally every sentence contains several
explosive stupidities and easy-to-spot demagogy. You are basically
working hard to deny all basic facts about Earth and life sciences,
along with tons of basics of physics – the importance of photosynthesis,
the importance of the Sun for the climate, the fact that ice ages bring
a much more substantial cooling than the warming caused by CO2, the
fact that some known episodes of climate change in the past have
occurred within decades so it's simply not true that it always takes
thousands of years. You also try to deny the self-evident point that
every individual human and animal is capable of instantaneous
adaptation to the temperature change by a degree or two. Your pretty
much explicit claim that one needs thousands of years to adapt to 1 °C
of warming is absolutely idiotic so that the intelligent third graders
will see it, too.

Moreover, your vague suggestion that the humans and other species are
significantly evolving in the time frame of thousands of years (during
the glaciation cycles) – when the temperature changes by several degrees
– is mostly rubbish, too. Real revolution occurs much more slowly than
the glaciation cycles. Glaciation cycles take tens or at most hundreds
of years; evolution normally needs millions of years. No significant
biological evolution has been taking place in between the phases of the
glaciation cycles; at most, one race of subspecies etc. became more
widespread than others.

Even though the anti-Dyson rant is so short, this essay could continue for hours.

It just drives me up the wall how incredibly lousy intellectual
standards are routinely tolerated e.g. in the MIT physics department
when some politically correct "causes" are being defended. You know,
communism has been crippling our society and the nation's morality in
many ways but I honestly don't remember a single example of Czechoslovak
communists' distorting influence of the natural sciences that could be
at least remotely compared to the climate alarmists' distortions of
photosynthesis, ice ages, solar output, sensitivity of plants on the
temperature, CO2, nutrients, water, whatever. The only good enough
analogy I can think of is the ban of genetics in the Soviet Union. I am
sure that you love to suggest that you're better than the Lysenkoists
but you are not.

The authors of the anti-Dyson rant in the Boston Globe should be deeply
ashamed and I encourage their students to spit into the authors' faces
and to demand a significant discount if they pay a tuition.

The Pliocene (/ˈplaɪəˌsiːn/;[1][2] also Pleiocene) Epoch (symbol PO[3]) is the epoch in the geologic timescale that extends from 5.333 million to 2.58[4] million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene.[5]
As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations.

Etymology

The Pliocene was named by Sir Charles Lyell. The name comes from the Greek words πλεῖον (pleion, "more") and καινός (kainos, "new")[6] and means roughly "continuation of the recent", referring to the essentially modern marine mollusc faunas. H.W. Fowler called the term (along with other examples such as pleistocene and miocene) a "regrettable barbarism" and an indication that even "a good classical scholar" such as Lyell should have requested a philologist's help when coining words.[7]

Subdivisions

In the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are:

In the Paratethys area (central Europe and parts of western Asia) the Pliocene contains the Dacian (roughly equal to the Zanclean) and Romanian (roughly equal to the Piacenzian and Gelasian together) stages. As usual in stratigraphy, there are many other regional and local subdivisions in use.
In Britain the Pliocene is divided into the following stages (old to young): Gedgravian, Waltonian, Pre-Ludhamian, Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian, Pastonian and Beestonian. In the Netherlands the Pliocene is divided into these stages (old to young): Brunssumian C, Reuverian A, Reuverian B, Reuverian C, Praetiglian, Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian. The exact correlations between these local stages and the ICS stages is still a matter of detail.[8]

Climate

Mid-Pliocene reconstructed annual sea surface temperature anomaly

The global average temperature in the mid-Pliocene (3.3–3 mya) was 2–3 °C higher than today,[9] global sea level 25 m higher[10] and the Northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma.[11] The formation of an Arctic ice cap is signaled by an abrupt shift in oxygenisotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds.[12] Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas.[13]

Paleogeography

Examples of migrant species in the Americas after the formation of the Isthmus of Panama. Olive green silhouettes denote North American species with South American ancestors; blue silhouettes denote South American species of North American origin.

Continents continued to drift, moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations. South America became linked to North America through the Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive large marsupial predator and native ungulate faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean.

Pliocene marine rocks are well exposed in the Mediterranean, India, and China. Elsewhere, they are exposed largely near shores.

Flora

The change to a cooler, dry, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, and grasslands spread on all continents (except Antarctica). Tropical forests were limited to a tight band around the equator, and in addition to dry savannahs, deserts appeared in Asia and Africa.

Fauna

Both marine and continental faunas were essentially modern, although continental faunas were a bit more primitive than today. The first recognizable hominins, the australopithecines, appeared in the Pliocene.

The land mass collisions meant great migration and mixing of previously isolated species, such as in the Great American Interchange. Herbivores got bigger, as did specialized predators.

Africa was dominated by hoofed animals, and primates continued their evolution, with australopithecines (some of the first hominins) appearing in the late Pliocene. Rodents were successful, and elephant populations increased. Cows and antelopes continued diversification and overtaking pigs in numbers of species. Early giraffes appeared, and camels migrated via Asia from North America. Horses and modern rhinos came onto the scene. Bears, dogs and weasels (originally from North America) joined cats, hyenas and civets as the African predators, forcing hyenas to adapt as specialized scavengers.

Birds

Titanis

The predatory South American phorusrhacids were rare in this time; among the last was Titanis, a large phorusrhacid that migrated to North America and rivaled mammals as top predator. Other birds probably evolved at this time, some modern, some now extinct.

Oceans

Oceans continued to be relatively warm during the Pliocene, though they continued cooling. The Arctic ice cap formed, drying the climate and increasing cool shallow currents in the North Atlantic. Deep cold currents flowed from the Antarctic.

The formation of the Isthmus of Panama about 3.5 million years ago cut off the final remnant of what was once essentially a circum-equatorial current that had existed since the Cretaceous and the early Cenozoic. This may have contributed to further cooling of the oceans worldwide.

Supernovae

In 2002, Narciso Benítez et al. calculated that roughly 2 million years ago, around the end of the Pliocene epoch, a group of bright O and B stars called the Scorpius-CentaurusOB association passed within 130 light-years of Earth and that one or more supernova explosions gave rise to a feature known as the Local Bubble.[14] Such a close explosion could have damaged the Earth's ozone layer and caused the extinction of some ocean life (at its peak, a supernova of this size could have the same absolute magnitude as an entire galaxy of 200 billion stars).[15][16]

About Me

My formal training is in chemistry. I also read a great deal of physics and biology. In fact I very much enjoy reading in general, mostly science, but also some fiction and history. I also enjoy computer programming and writing. I like hiking and exploring nature. I also enjoy people; not too much in social settings, but one on one; also, people with interesting or "off-beat" minds draw me to them. I also have some interest in Buddhism.

These days I get a lot more information from the internet, primarily through Wiki. Some television, e. g., documentaries, PBS shows like "Nova" and "Nature".

My favorite science writers are Jacob Bronowski ("The Ascent of Man") and Richard Dawkins (his "The Blind Watchmaker" is right up there up Ascent). I also have a favorite writer on Buddhism, Pema Chodron. Favorite films are "Annie Hall" (by Woody Allen), "The Maltese Falcon", "One Flew Over The Cuckoo's Nest", "As Good As It Gets", "Conspiracy Theory", Monty Python's "Search For The Holy Grail" and "Life of Brian", and a few others which I can't think about at the moment.

I love a number of classical works (Beethoven's "Pastoral", "Afternoon Of A Fawn" and "Clair De Lune" by Debussey , Pachelbel's "Canon" come to mind. My favorite piece is probably Gershwin's "Rhapsody in Blue". But I also enjoy a great deal in modern music, including many jazz pieces, folk songs by people like Dylan, Simon and Garfunkel, a hodgepodge of pieces by Crosby, Stills, and Nash, Niel Young, and practically everything the Beatles wrote.

My life over the last few years has been in some disarray, but I am finally "getting it together.". As I am very much into the sciences and writing, I would like to move more in this direction. I also enjoy teaching. As for my political leanings, most people would probably describe as basically liberal, though not extremely so. My religious leanings are to the absolutely none: I've alluded to my interest in Buddhism, but again this is not any supernatural or scientifically untested aspect of it but in the way it provides a powerful philosophy and set of practical, day to day methods of dealing with myself and the other human beings.